A large water storage in central Victoria has filled past its capacity and is now releasing water into the river below it. The release follows a long and wet winter across the region.
Downstream, a town that has suffered severe flooding in recent years is watching the river closely. The authority that manages the storage says a spilling lake does not mean a flood is on the way.
What is happening at Lake Eppalock
The storage in question is Lake Eppalock, a reservoir on the Campaspe River near Bendigo. Goulburn-Murray Water operates the lake and has confirmed it is effectively spilling. The lake pushed past 100 per cent capacity after a wet winter.
A reservoir stores water behind a dam wall. When the lake is full, the extra water can no longer be held. It flows over the top and down the river. That is what is happening now. When the storage is full, any extra inflow has nowhere to go but down the river.
The numbers show how much water arrived. More than 100,000 megalitres flowed into Lake Eppalock since the start of August. That is a very large volume for a reservoir that fills slowly through the colder months.
Central Victoria has had a wet 2026 overall. Bendigo Airport recorded 104 millimetres in August, 110 millimetres in June and 106 millimetres in March. Months like these leave the catchment full and the ground soaked.
The dam wall at Lake Eppalock. Photo: Mattinbgn via Wikimedia Commons (CC BY 3.0). Image for reference only.
Spilling does not mean flooding
A spilling lake is not the same as a flooding river. Goulburn-Murray Water says spilling does not automatically mean flooding downstream. Current flows remain well within the river channel.
The immediate rise downstream of the dam is only small. Releases are managed under the Water Act 1989 and set operating procedures. The operator controls how much water leaves the lake. The key difference is the speed and volume of the flow.
Think of it this way. A spill sends water down the channel in a controlled flow. The water stays between the banks. A flood happens only when the river leaves its banks and spreads onto the land.
Why Rochester watches closely
Rochester, a town in the Campaspe Shire, has good reason to stay alert. The town flooded badly in October 2022 when the Campaspe River burst its banks. More than 90 per cent of homes were inundated. The town sits downstream of the dam on the same river.
Rochester flooded again about 15 months later. Heavy rain in December 2023 and January 2024 pushed the river over its banks once more. Two floods in a short time left many residents wary of any rise in the river.
Some Rochester residents have long campaigned for less water to be held in Lake Eppalock in late winter and spring to reduce flood risk.
What could raise the risk
The main risk is the lack of room left in the lake. A flood risk assessment cited in reporting says a rainfall event of just 10 millimetres could produce an estimated 8,000 to 12,000 megalitres of inflow when the storage has no airspace. That is a lot of water moving very quickly.
Airspace is the empty room at the top of a reservoir. It is the spare capacity that can catch extra water. When the lake is full, that room is gone. New rain runs straight over the spillway and into the river.
That is the key point for Rochester. A full lake can absorb nothing. Any sudden downpour in the catchment moves quickly downstream toward the town.
The North Central Catchment Management Authority is starting an environmental spring flow down the Campaspe River in the week of 14 September. This planned release supports the health of the river and is separate from the spill.
Where to follow the warnings
Do not treat a spilling lake as a flood warning on its own. The useful signals come from official sources.
Watch for updates from Goulburn-Murray Water, which publishes storage and release information. Follow emergency services for flood watches and warnings. The North Central Catchment Management Authority tracks river conditions. Warnings will name the river and the areas likely to be affected.
The risk picture changes if heavy rain is forecast on top of a full lake. In that case the river may rise quickly and official warnings will follow. Check these sources before and during any wet weather.
A healthier lake in other ways
Flood risk is not the only story at Lake Eppalock. A blue-green algae warning for the lake, issued on 30 March 2026, has been lifted after 129 days. That is a separate issue from flooding, but a welcome one for locals and visitors.
Conclusion
Lake Eppalock is full and spilling, but that alone is not a flood warning for Rochester. The river is currently within its channel and flows are managed.
The real test is what the weather does next. A large rainfall event on a full lake would change the picture quickly. Rochester residents know this better than most after the floods of 2022 and 2023 to 2024.
For now, watch the official river and weather warnings rather than the lake level alone. Spilling is normal for a full reservoir. Flooding is a different and far more serious event. Staying informed is the simplest way to stay safe.
To explore Rochester and the wider Murray region in more depth, visit the Every Suburb Victoria guide.
Works Cited
Hancock, Carla. "A Full Lake Eppalock Raises Flood Fears Along Campaspe River." Bendigo Advertiser, 15 Sept. 2026, https://www.bendigoadvertiser.com.au/story/9348224/a-full-lake-eppalock-raises-flood-fears-along-campaspe-river/.